Venereal disease is a serious public health problem in the United States. Effective control measures will depend on a better understanding of the biology and immunology of the diverse microbes responsible for these infections. This proposal is a collaborative effort by investigators at Cornell University Medical College and the Rockefeller University to study in depth the following four areas of research: (1) immunity to Neisseria gonorrhoeae, (2) genetic transformation and antibiotic sensitivity of Neisseria gonorrhoeae, (3) immunity to Treponema pallidum, and (4) biology of Trichomonas vaginalis. Summaries of the objectives for each research project are included in Section 4, Scientific Programs. This collaborative grant will promote the initiation by other colleagues in the investigation of the biology of infectious agents associated with sexually transmitted diseases and also be instrumental in forming a basis for future clinical and epidemiological studies of these diseases in New York City.